DE102021118764A1 - Stator for an electrical machine, electrical machine, method for manufacturing a stator - Google Patents

Abstract

The invention relates to a stator for an electrical machine, the stator comprising a laminated stator core, an end component being arranged on an end face of the laminated stator core, characterized in that the end component has an electrical insulation coating.

Description

The invention relates to a stator for an electrical machine, the stator comprising a laminated stator core, with an end component being arranged on an end face of the laminated stator core. Furthermore, the invention relates to an electrical machine comprising such a stator. Furthermore, the invention relates to a method for producing such a stator.

Such electrical machines can be used, for example, as electric motors in partially or fully electrically operated vehicles.

The stator of an electrical machine contains stator coils which, due to their spatial arrangement and the superimposed voltages applied to the coils, generate a rotating magnetic field. These stator coils can be made from different semi-finished products and in different geometries, including flat wires in the form of a hairpin geometry.

Guide devices, such as guide combs, are known for deforming the hairpins. The guide geometry can be provided using external tools, so-called fingers, or an end component attached to the stator core. The main task of such an end component is typically the provision of the guide geometry on the end face of the stator core during the manufacturing process of the stator winding.

It is known from DE 102019207889 A1, for example, that a bending aid is provided in a bending process step, which enables a process-reliable bending process of the rod ends protruding from an axial stator end face. The bending aid of DE 102019207889 A1 is a disc with passage openings through which the rod ends are guided.

According to the prior art, such forehead components are typically made of plastic using an injection molding process. However, the high-performance thermoplastics used, such as polyphenylene sulfide (PPS) or polyetheretherketone (PEEK), generally have low tracking resistance.

A crucial aspect of electrical machines and in particular their stators is to avoid insulation problems in order to reduce the susceptibility to faults, especially in the case of environmental influences that affect the machine over the lifetime of the electrical machine.

Against this background, the task arises of providing a stator for an electrical machine with which the service life can be increased and/or the susceptibility to faults can be improved, preferably in a cost-effective manner.

To achieve the object, a stator for an electrical machine is proposed, the stator comprising a laminated stator core, an end component being arranged on an end face of the laminated stator core, characterized in that the end component has an electrical insulation coating.

With the help of the electrical insulation coating of the end component, it is possible to reduce the susceptibility to faults and to reduce or prevent damage in the event of a fault in the insulation. It is particularly advantageously conceivable according to the invention that the end component itself is an efficient part of the insulation system of the stator due to the use of the electrical insulation coating.

According to the invention, different insulation systems or types of insulation are conceivable for the stator windings of the stator. In particular in the case of stator windings that are constructed without slot base insulation or with an alternative slot base insulation, for example using plastic sleeves instead of the slot insulation paper that is typically used, the end component according to the invention can be used particularly advantageously as part of the electrical insulation system, with the electrical insulation coating achieving advantageous insulation.

In addition, it is conceivable that in the event of a fault in the conductor and/or slot insulation, for example also when the insulation system is configured using slot insulation paper, a creepage path can arise between live conductor surfaces and/or the laminated core of the stator. Such creepage paths can be prevented in a particularly advantageous manner with the aid of the electrical insulation coating of the end component according to the invention. The end component according to the invention can protect the electrical machine from damage in such fault cases due to the advantageous electrical properties that can be achieved with the aid of the insulating coating.

Another advantage is that the increased insulation strength that can be achieved with the help of the insulation coating reduces the axial installation space requirement of the winding overhang in the applications described and thus the power density of the machine can be increased.

According to one embodiment of the present invention, an electrical insulation coating of the front component is to be understood in particular as a coating of the front component to increase the tracking resistance of the front component.

Advantageous configurations of the invention can be found in the dependent claims.

According to an advantageous embodiment, it is provided that the end component comprises a base body, with the electrical insulation coating of the end component having a higher insulation resistance and/or tracking resistance than the base body of the end component. The insulating coating is preferably applied to the base body, in particular over the entire surface or over part of the surface.

It is possible according to an embodiment of the present invention that the insulating coating is made of a material or a material composition, wherein the material or the material composition of the insulating coating has a CTI value for the tracking resistance of greater than or equal to 175. The tracking resistance is characterized with the CTI value (Comparative Tracking Index). The CTI value states in particular up to which highest test voltage, measured in volts, the base material shows no tracking when 50 drops of standardized electrolyte solutions are dropped. "Tracking" here means in particular that the base material becomes conductive under voltage. Measurements are taken on the etched surface, with a drop falling between two platinum electrodes every 30 seconds. The failure criterion is a leakage current of >0.5 A. The CTI value is measured, for example, in accordance with IEC 60112:2020 (Method for the determination of the proof and the comparative tracking indices of solid insulating materials).

According to an advantageous embodiment, it is provided that the material or the material composition of the insulating coating has a CTI value “alpha” for the tracking resistance of greater than or equal to 175, preferably 400≦alpha<600, particularly preferably 600≦alpha.

According to an advantageous embodiment, it is provided that the end component is designed as an end plate. The end disk is preferably attached directly to the end face of the laminated core of the stator.

According to an advantageous embodiment, it is provided that the base body of the end component is made partially or completely from one or more high-performance thermoplastics, in particular from one or more glass fiber-reinforced high-performance thermoplastics. The base body of the end component, in particular the end disk, is manufactured using polyphenylene sulfide (PPS) or polyether ether ketone (PEEK), for example. For manufacturing reasons and the thermal, chemical and mechanical boundary conditions prevailing during operation of the stator, the base body is particularly preferably made from one or more glass fiber reinforced high-performance thermoplastics, for example PPS GF40. Such high-performance thermoplastics generally have a low tracking resistance, in particular a CTI value of less than 175. According to one embodiment of the present invention, the advantageous electrical properties of the end component are particularly advantageously achieved by the additional application of the electrical insulation coating to the base body.

According to an advantageous embodiment, it is provided that a guide geometry and/or guide device for a winding interconnection for hairpins of the stator is formed with the aid of the end component. As a result, the end component can be used particularly advantageously for the winding interconnection or formation and at the same time have advantageous electrical properties for insulating and protecting the stator. According to one embodiment of the present invention, it is conceivable that the hairpins—in particular after the hairpins have been formed and the leg ends have been stripped—are inserted into the stator and widened. The hairpins are preferably introduced into axial slots of the stator in an axial direction of the stator. To produce the winding circuitry, the hairpins are preferably bent in a circle in opposite directions (“twist”) basket by basket, so that the stripped ends of the pins are paired one above the other. A guide geometry on the front side of the laminated core of the stator is used to bend or twist the pins. This guiding geometry is preferably provided with the aid of the end component attached to the end face of the laminated core of the stator, in particular the end disk. The front component is additionally used in a particularly advantageous manner to support the hairpins and thus to prevent damage to the hairpins on the front edges of the slot openings.

According to an advantageous embodiment, it is provided that a further end component is arranged on a further end face of the laminated stator core opposite the end face, the further end component having a further electrical insulation coating. The further end component preferably comprises a further body. The further end component is preferably designed as an end plate.

According to an advantageous embodiment, it is provided that the additional insulating coating is made of an additional material or an additional material composition, wherein the additional material or the additional material composition has a CTI value “beta” for the tracking resistance of greater than or equal to 175, preferably of 400 ≤ beta < 600, more preferably 600 ≤ beta. In particular, it is conceivable that the insulating coating of the end component and the further insulating coating of the further end component are made of the same material or the same material composition. It is particularly preferably possible for the further end component to assume the same functions as the end component and/or for the further end component to be designed at least essentially identically to the end component.

Another subject of the invention is an electrical machine, comprising a stator according to an embodiment of the present invention.

A further object of the invention is a method for producing a stator according to an embodiment of the present invention, wherein during production of the stator the end component is arranged on an end face of the laminated stator core, the end component having an electrical insulation coating.

According to one configuration of the present invention, in particular of the method, it is conceivable that a guide geometry and/or guide device is provided with the aid of the end component during formation of the stator winding. It is also possible that the end component is additionally or alternatively used to support the components of the winding in order to prevent damage to the winding components at the end edges of the slot openings.

In the case of the electric machine and the method for producing a stator, the same advantages can be achieved and the same features can be applied that have already been described in connection with the stator according to the invention or an embodiment of the stator according to the invention.

• 1A eine schematische Darstellung eines Flachdrahts mit Schenkeln gemäß einer Ausführungsform der vorliegenden Erfindung;
• 1B eine schematische Darstellung eines Hairpins gemäß einer Ausführungsform der vorliegenden Erfindung;
• 2 eine schematische Darstellung eines Statorblechpakets nach dem Einstecken der Hairpins gemäß einer Ausführungsform der vorliegenden Erfindung;
• 3 eine schematische Darstellung eines Statorblechpakets nach dem Verschweißen der Hairpins gemäß einer Ausführungsform der vorliegenden Erfindung; und
• 4 eine schematische Darstellung eines Stators gemäß einer Ausführungsform der vorliegenden Erfindung.

Further advantages and details of the invention are to be explained below with reference to the exemplary embodiments illustrated in the drawings. Herein shows:

• 1A 12 is a schematic representation of a flat wire with legs according to an embodiment of the present invention;
• 1B a schematic representation of a hairpin according to an embodiment of the present invention;
• 2 a schematic representation of a stator core after the insertion of the hairpins according to an embodiment of the present invention;
• 3 a schematic representation of a stator core after the welding of the hairpins according to an embodiment of the present invention; and
• 4 a schematic representation of a stator according to an embodiment of the present invention.

In 1A a flat wire with two legs 2, 2' is shown schematically. The legs each have a stripped end region 3, 3'. In 1B A hairpin 10 is shown, which is formed using a flat wire and can be plugged into a stator.

In 2 a schematic representation of a hairpin stator after the insertion of the hairpins 10 is shown. For this purpose, the hairpins 10 were introduced into axial grooves of the laminated core 20 of the stator. The laminated core 20 of the stator has an end face 21 and a further end face 22 opposite the end face 21 . In 3 FIG. 12 is a schematic representation of the hairpin stator of FIG 2 shown after welding.

In 4 1 shows a schematic illustration of a stator 1 for an electrical machine according to an embodiment of the present invention. The stator 1 is a hairpin stator. On its axial end face 21, the laminated core 20 of the stator has an end component 30, in particular an end disk. A further end component 30 ′, in particular a further end disk, is attached to the opposite, further end face 22 of the laminated stator core 20 . The forehead component 30 comprises a base body which is coated with an electrically insulating coating. The application of this coating to the end component 30 increases the insulating strength of the end component 30 . For this purpose, the insulating coating consists of a material or a material composition with a CTI value “alpha” for the tracking resistance of alpha greater than or equal to 175, preferably 400≦alpha<600, particularly preferably 600≦alpha. In this way, the end component 30 can protect the stator and the electric machine particularly efficiently in the event of a fault and prevent the occurrence of prevent high leakage currents. Furthermore, the end component 30 can assume insulating functions due to the electrical insulating coating, which advantageously makes it possible to dispense with slot base insulation in the stator windings or to use an alternative slot base insulation, such as plastic sleeves instead of the conventionally used slot insulation paper. The further end component 30 ′ is preferably constructed in the same way as the end component 30 . The end component 30 and the further end component 30 ′ can be used to deform the hairpins when the stator 1 is manufactured. For this purpose, the end components 30, 30′ provide a guiding geometry on the end face of the laminated core of the stator during the manufacturing process of the stator winding. The end members 30, 30' can also be used to support the components of the winding to prevent damage to the winding components 40, 40' at the end edges of the slot openings.

Reference List

1

stator

2

leg

2'

leg

3

end area

3`

end area

10

hairpin

20

stator core

21

face

22

further front side

30

forehead component

30`

another forehead component

40

winding components

40'

winding components

Claims (10)

Stator (1) for an electrical machine, the stator (1) comprising a stator lamination stack (20), an end component (30) being arranged on an end face (21) of the stator lamination stack (20), characterized in that the end component (30 ) has an electrical insulation coating. Stator (1) after claim 1 , wherein the forehead component (30) comprises a base body, wherein the electrical insulating coating of the forehead component (30) has a higher insulation resistance and/or tracking resistance than the base body of the forehead component (30). Stator (1) according to one of the preceding claims, wherein the insulating coating is made of a material or a material composition, wherein the material or the material composition of the insulating coating has a CTI value for the tracking resistance of greater than or equal to 175. Stator (1) after claim 3 , where the material or material composition of the insulating coating has a CTI “Alpha” value for tracking resistance of 400 ≤ Alpha ≤ 600 or of 600 ≤ Alpha. Stator (1) according to one of the preceding claims, wherein the end component (30) is designed as an end plate. Stator (1) according to one of the preceding claims, wherein the base body of the end component (30) is made partially or completely from one or more high-performance thermoplastics, in particular from one or more glass-fibre reinforced high-performance thermoplastics. Stator (1) according to one of the preceding claims, wherein a guide geometry and/or guide device for a winding interconnection for hairpins of the stator (1) is formed with the aid of the end component (30). Stator (1) according to one of the preceding claims, wherein a further end component (30`) is arranged on a further end face (22) of the stator lamination stack (20) opposite the end side (21), the further end component (30`) having a further electrical Has insulation coating. Electrical machine, comprising a stator (1) according to one of the preceding claims. Method for producing a stator (1) according to one of Claims 1 until 8th , wherein during the manufacture of the stator (1), the end component (30) is arranged on an end face (21) of the laminated stator core (20), the end component (30) having an electrical insulating coating.

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